ENVIRONMENTAL DAMAGE OF CAST Ni-BASE SUPERALLOY K17
K17镍基铸造高温合金环境损伤的研究

Rupture and tensile properties of K17 before and after thermal expo- sure in vacuum, air and hot corrosion environments have been investigated. The results show that vacuum exposure essentially does not affect the rupture lives, but it results in the decrease of high temperature tensile strength and increases of rup- ture and high temperature tensile ductilities; air or hot corrosion environmental ex- posure make the alloy degradation: severely reduce the rupture and high temperature tensile properties, hot corrosion environmental exposure being more harmful. The former causes grain boundary oxidation and depletion of Cr, and the later makes the sulphurization at grain boundaries. That results in the concentration of S and depletion of Cr at grain boundaries and, consequently, weakens the grain bounda- ries.